U.S. Pat. No. 4,817,611 to Arzbaecher et al. entitled "Esophageal Electrocardiography Electrodes" discloses a form of bipolar electrode usable for esophageal cardiac pacing or cardiac monitoring. The bipolar electrode of the Arzbaecher et al. patent has a molded plastic body which lockingly carries first and second spaced-apart conducting bands. The disclosure and figures of the Arzbaecher et al. patent are incorporated herein by reference.
Other types of esophageal insertable devices are known. Some of these have regions or balloons which can be inflated for the purpose of blocking portions of the esophagus or for the purpose of positioning the unit in the esophagus. These devices require a fluid such as air or saline for inflation.
None of the known devices provide a simple mechanically expandable electrode carrying member which, as a result of expansion, could provide improved contact between the interior surface of the esophagus and the conducting elements of the electrode. Thus, there continues to be a need for esophageal catheters of a type which can be easily expanded upon insertion and yet are cost effective to manufacture.